A major challenge facing developed nations is dealing with the volumes of waste produced. Efforts have been made, in particular, in relation to the recycling of plastics and paper waste. Approaches to the recycling of plastics have focused upon processes where plastics are sorted into the various types and controlled proportions are utilised to produce recycled products.
A report entitled “Assessing the potential for post-use plastics waste recycling—predicting recovery in 2001 and 2006” produced by the Association of Plastics Manufacturers in Europe identified the main constraints for improving recycling rates for plastic as:    i/ the imbalance between the waste collectable and the potential end-markets for the recycled plastics    ii/ the presence of large quantities of mixed plastics waste where the difficulties and energy consumed in separating into homogenous fractions and cleaning outweigh the environmental gain of mechanical recycling.
The report considered there to be an upper limit to potential demand for mechanically recycled plastics. This report reflects the common mind set of those in the industry that tightly control sorting is required to produce a valuable product. It also reflects the commonly held perception that there is a limited marked for the types of articles that may be produced.
In the report “SIRA International (1999). Australian Plastics Materials Recycling Survey—Report for Plastics and Chemicals Industries Association. Canberra, Australia” the major problems facing recyclars were identified as:                Separation of difficult plastics        Contamination between polymers        Contaminated waste        Plastics re-processing is highly labour intensive for low returns        Demand is unbalanced with supply        Not enough end users        Collection and separation        
Plastic recyclers currently recycle plastics into seven types as follows:    Code 1: Polyethylene Terephthalate (PET or PETE)    Code 2: High Density Polyethylene (HOPE)    Code 3: Vinyl (Polyvinyl Chloride or PVC)    Code 4: Low Density Polyethylene (LOPE)    Code 5: Polypropylene (PP)    Code 6: Polystyrene (PS)    Code 7: Other
Tightly controlled sorting is expensive and is a significant cost component in current recycling processes. Where tightly controlled sorting has been required it has been difficult to produce a marketable product economically. The characteristics of many products produced in such recycling processes have been considered to be inferior.
There has also been a prejudice against the use of polyethylene film in recycling processes. In “Siegler, T. & Perkins, R. (1999). Sorting Plastic Bottles for Recycling. Ascotney, Vermont: DSM Environmental Services for The American Plastics Council” the following points were noted:    “Acceptance of even small amounts of recyclables in plastic bags will significantly reduce equipment efficiency unless all of the film is removed with a film removal system at the front end.”and    “The composition of material delivered to the MRF (materials recovery facility) has a significant impact on processing efficiency. Contaminants entering MRFs 5, 6, and 7 represented between 3.7% and 6.7% of the incoming material. This seemingly small amount of incoming contamination was responsible for between 31 and 67% of sorting labour at these the MRFs.”and    “Increased public education is necessary to better inform participating households which plastic containers are acceptable in the recycling program.”
Rathje, W and Murphy, C. cite as one of the “Five Major Myths about Garbage and Why They're Wrong” that:    “The biggest problem faced by recycling is not the technological process of turning one thing into another. Anything can be recycled—and would be if demand for what it could be recycled into were great enough. The key, then, is demand, and demand for many recyclables is often soft.”
To date the most commercially attractive recycling progresses have been those utilising industrial waste. Industrial waste may typically consist of large batches of one type of plastics which avoids the need for any sorting process.